| Survey Yr | Annual Discgage (m3/s) | Discharge through Forcados (%) | Discharge through Nun (%) |
| 1953/1954 | NA | 55 | 45 |
| 1959/1960 | NA | 60 | 40 |
| 1978 | 2499 | 55 | 45 |
| 1979 | 2464 | 55 | 45 |
| 1980 | 2358 | 55 | 45 |
| 1981 | 2364 | 55.01 | 44.09 |
| 1982 | 1871 | 54 | 46 |
| 1983 | 1267 | 55.01 | 44.99 |
| 1984 | 1353 | 55 | 45 |
| 1985-1997 | NA | NA | NA |
| 1998 | 5189 | 46 | 54 |
| 2012 | 31,000 | 46 | 54 |